Printer Device

ABSTRACT

A compact and lightweight design for a printer device that is optimally portable. A printed circuit board assembly  22  incorporated in the printer device includes a control printed-circuit board  22   a  and a power printed-circuit board  22   b  arranged substantially in L-shaped fashion. A connector  23  electrically couples boards  22   a  and  22   b  to each other. The power printed-circuit board, on which large current flows, is located near a large current source. A charge circuit, battery contacts and a control circuit for applying voltage to a thermal head are mounted and concentrated on the sole power printed-circuit board. The control printed-circuit board  22   a  for controlling recording paper and ink ribbon feed, which require only small current, is located near a small current source, such as an actuator needed for feeding recording paper and an ink ribbon including a recording paper/ribbon feeding mechanism  17.  The circuits for controlling recording paper feed and ink ribbon feed are mounted and concentrated on the sole control printed-circuit board  22   a.  The substantially L-shaped printed-circuit board assembly, serving as a motherboard, is incorporated in the printer device to realize the capabilities of the printer device.

[0001] This application claims benefit of Japanese Application No. 2000-69928 filed in Japan on Mar. 14, 2000, the contents of which are incorporated by this reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a printer device, or more particularly, to a printer device that is so compact and lightweight as to be portable.

[0004] 2. Description of the Related Art

[0005] Personal computers and video recorders have been popular in recent years. Various types of printer devices capable of recording images produced by equipment including the personal computer and video recorder have been proposed, and the needs for the printer devices have increased. There is therefore an increasing demand for a printer device that is inexpensive and capable of producing high-definition print images. Moreover, a portable printer device that is compact and lightweight is highly demanded along with the needs for a mobile printer device that permits printing at any time in any place.

[0006] In a typical thermal printer device, a color hard-copy ink sheet having three dyes of yellow (Y), magenta (M), and cyan (C) cyclically applied thereto in predetermined order is circulated based on a video signal sent from an information source. A thermal head is heated in order to sublimate the dyes on the ink sheet. Thus, one screen image is printed in colors on recording paper (thermal transfer recording paper). Moreover, in the printer device, the length of time during which current is fed to the thermal head is controlled in order to adjust the amounts of dyes to be sublimated. Gray scaling is thus controlled. After an image is recorded in this way, a recording paper transporting mechanism included in the printer device transports recorded recording paper, and feeds it to and stores it in, for example, a finished paper case. Thus, a recording process for one screen image (one page) is completed.

[0007] Even the above type of thermal printer device is demanded to be so compact and lightweight as to be portable. As a related art, a printer device has been proposed in Japanese Unexamined Patent Publication No. 11-157113.

[0008] In the proposed printer device, an ink ribbon having thermal transfer inks applied to a thin film and recording paper are transported while being pressed by a thermal head and a platen roller. Current is then fed to an exothermic resistor included in the thermal head, thus heating the exothermic resistor. The exothermic resistor transfers the thermal transfer inks on the ink ribbon onto the recording paper, whereby printing is achieved. The printer device is characterized in that a thermistor is used to measure temperature for the purpose of setting the next printing start time instant. Thus, the printer device is readily realized as a compact printer device having the features that the thermal head enjoys excellent heat efficiency and sheets of recording paper can be printed successively.

[0009] Moreover, the thermal head employed in the printer device includes a bar-like glass member that is attached along one edge of a printed-circuit board. An exothermic unit including a plurality of exothermic resistors is formed along the bar-like glass member. The exothermic resistors are connected to a plurality of independent electrodes and a common electrode. A thermistor connected to the common electrode and a plurality of driving ICs connected to each of the plurality of independent electrodes and the common electrode are mounted on the printed-circuit board. Consequently, power consumed by the thermal head can be set to a small value. Besides, a radiating plate employed in the related art becomes unnecessary. Therefore, the thermal head can be adapted to a printer device that is so compact and lightweight as to be portable.

[0010] For realizing a portable printer device, it is, as already known, important to design the printer device to be compact and lightweight. Another important factor for realizing a portable printer device is whether the printer device can be driven for printing using only a battery as well as an ac power line. Moreover, it would be found user-friendly if a charge circuit for charging the battery is incorporated in the printer device.

[0011] The improved printing performance of the conventional printer device and the compact and lightweight design thereof have been attained by improving the thermal head and obviating the necessity of the radiating plate. Any description has not been made of where a circuit-printed board should be placed in practice or how circuit elements should be mounted on the circuit-printed board in practice in order to attain the compact and lightweight design of the entire printer device. This poses a problem in that the printer device cannot be designed fully compactly. Moreover, the battery that is an important component of a portable printer device and the charge circuit for charging the battery are not included in the conventional printer device. The conventional printer device therefore fails to satisfy users who want a portable printer device.

OBJECT OF THE INVENTION

[0012] Accordingly, an object of the present invention is to provide a printer device that is so compact and lightweight as to be optimally portable.

SUMMARY

[0013] A printer device in accordance with the present invention comprises a control printed-circuit board, a power printed-circuit board, and a coupling means. The control printed-circuit board is placed on the bottom of the printer device and includes a control circuit that controls at least one of paper feed and ink ribbon feed. The power printed-circuit board is placed along one side surface of the printer device, and includes a charge circuit that charges a rechargeable battery brought into contact with battery contacts connected to the charge circuit. The coupling means electrically couples the control printed-circuit board to the power printed-circuit board.

[0014] According to the present invention, the control printed-circuit board including the control circuit that controls at least one of paper feed and ink ribbon feed is placed on the bottom of the printer device. The power printed-circuit board including the charge circuit is located along one side surface of the printer device. The charge circuit charges the rechargeable battery brought into contact with the power contacts connected to the charge circuit. The control printed-circuit board and the power printed-circuit board are electrically coupled to each other using the coupling means. Consequently, the printed-circuit boards and the placement of the printed-circuit boards are most suitable for the compact design of the printer device from the structural viewpoint.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view showing the overall configuration of a printer device in accordance with an embodiment of the present invention;

[0016]FIG. 2 is an exploded perspective view showing the internal configuration of the printer device shown in FIG.

[0017]FIG. 3 is a sectional view of the printer device in accordance with the present invention showing the placement of printed-circuit boards in the printer device in accordance with the present invention;

[0018]FIG. 4 is a perspective view showing the printed-circuit boards shown in FIG. 3 while viewing them from the front side of the printer device;

[0019]FIG. 5 is a perspective view showing the printed-circuit boards shown in FIG. 3 while viewing the printed-circuit boards from the rear side of the device; and

[0020]FIG. 6 is a sectional view of the printer device shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of the present invention will be described with reference to the drawings below.

[0022]FIG. 1 is a perspective view showing the overall configuration of a printer device in accordance with an embodiment of the present invention.

[0023] As shown in FIG. 1, the housing of a printer device 1 in accordance with the present embodiment consists of a body cover 2 and a body bottom 3. The body cover 2 encloses various mechanisms, components, and printed-circuit boards that are necessary for printing. The body bottom 3 is attached to the lower part of the body cover 2.

[0024] A paper feed cassette loading opening 2 a through which a paper feed cassette 5 is loaded is formed in the front surface of the body cover 2 of the device 1 (left forward part of the drawing). A plurality of sheets of recording paper 6 can be stowed in the paper feed cassette 5. The paper feed cassette 5 is loaded through the paper feed cassette loading opening 2 a so that it can be unloaded freely.

[0025] Moreover, an open/close lid 4 a capable of being opened or closed is located at a right position on the body bottom 3 coincident with the position of the paper feed cassette loading opening 2 a. The open/close lid 4 a is closed to block the paper feed cassette loading opening 2 a after the paper feed cassette 5 is unloaded from the printer device. The open/close lid 4 a has a locking means 4 c that retains the closed state of the lid 4 a. The open/close lid 4 a is locked owing to the locking means 4 c and a stopper means (not shown) located at a right position on the body cover 2 coincident with the position of the locking means 4 c.

[0026] An opening 2 f is formed in a right side surface of the body cover 2 with the body cover 2 viewed from the front side of the printer device. A main frame 12 b is exposed through the opening 2 f and incorporated in the printer device. An ink cassette insertion port 2 b through which an ink cassette 7 is inserted is formed in the main frame 12 b. The ink cassette 7 has an ink ribbon 7 a wound therein. The ink ribbon 7 a has a plurality of thermal transfer inks applied repeatedly to a film-like base material. The thermal transfer inks of yellow (Y), magenta (M), and cyan (C) ink, and a transparent overcoat ink (OP) are applied to the film-like base material in that order (in order of the yellow, magenta, cyan, and overcoat inks).

[0027] Moreover, the body cover 2 has an open/close lid 4 b capable of being opened or closed. The open/close lid 4 b is closed to block the opening 2 f. Similarly to the open/close lid 4 a, the open/close lid 4 b has a locking means 4 d that retains the closed state of the open/close lid 4 b. The open/close lid 4 b is locked owing to the locking means 4 d and a stopper means (not shown) formed at a right position on the body cover 2 coincident with the position of the locking means 4 d.

[0028] A battery attachment groove 2 c is formed in the back surface of the body cover 2 (right backward part of the drawing), and used to freely detachably attach a battery 8 to the body cover 2. The battery 8 serves as a driving power supplying means and is essential to a portable device. An attachment member 8 a formed in the attachment surface of the battery 8 is fitted in the battery mounting groove 2 c, whereby the battery 8 is attached to the body cover 2. Stoppers 8 c formed on the top of the battery attachment member 8 a are engaged with stopping means (not shown) formed at right positions in the battery attachment groove 2 c coincident with the positions of the stoppers 8 c, whereby the attached state of the battery 8 can be retained.

[0029] Moreover, a plurality of battery contacts 8 b is formed on the face of the attachment member 8 a of the battery 8. Power accumulated in the battery 8 is supplied into the interior of the printer device 1 through the plurality of battery contacts 8 b. When the battery 8 is fitted in the battery attachment groove 2 c, the contacts 8 b come into contact with battery contacts (not shown) formed on the back surface of the printer device 1, and conduct electricity to the battery contacts. Thus, power is supplied to the interior of the printer device 1.

[0030] On the other hand, a memory card connector (not shown) is formed in the center of the side surface of the body cover 2 other than the side surface thereon in which the ink cassette insertion port 2 b is formed. A memory card 9 in which an image information signal according to which an image is printed is recorded, for example, a smart medium is loaded through the memory card connector so that it can be unloaded freely. When the memory card 9 is loaded through the memory card connector (not shown), the image information signal needed to print an image is fetched from the memory card 9.

[0031] Moreover, a DC connector (not shown) is formed in the rear part of the same side surface. A DC plug 10 used to transform ordinary alternating voltage into direct voltage and apply the direct voltage to the printer device 1 is mated with the DC connector so that it can be unmated freely. The ordinary alternating voltage is applied through an AC plug 10 a inserted into a mains outlet that is not shown. The alternating voltage is transformed into the direct voltage within the AC plug or by an AC-to-DC transformer (not shown) interposed between the AC plug 10 and the DC plug 10. The resultant direct voltage is applied to the interior of the printer device as driving power for the printer device 1 through the DC plug 10.

[0032] In the printer device 1 in accordance with the present embodiment, an image information signal is fetched not only from the memory card 9 but also from, for example, a personal computer or video recording/reproducing equipment. Specifically, a PC connector (not shown) is formed in the frontal part of the side surface of the body cover 2 in which the memory card connector (not shown) is formed. A PC connector 11 attached to a cable extending from the personal computer or video recording/reproducing equipment is mated with the PC connector (not shown) so that it can be unmated freely. In the printer device 1 in accordance with the present embodiment, various image information signals can be fetched not only from the memory card 9 but also through the PC connectors 11 attached to cables extending from various pieces of imaging equipment. This results in an expanded range of applications of the printer device.

[0033] Moreover, the paper feed cassette 5 employed in the printer device 1 can accommodate a plurality of sheets of recording paper 6. The paper feed cassette 5 has a detachable cover 5 a as the top thereof. The cover 5 a has a notch formed along the distal edge thereof included in the distal part of the paper feed cassette 5 that is inserted first. The topmost sheet of the plurality of sheets of recording paper 6 stowed in the paper feed cassette 5 is exposed through the notch. When the paper feed cassette 5 is inserted, the distal part of the paper feed cassette 5 is used to place the paper feed cassette 5 in position. A paper feed roller (not shown) located inside the printer device 1 comes into contact with one sheet of recording paper 6 exposed through the notch of the cover 5 a. When the paper feed roller is driven to rotate, the one sheet of recording paper 6 is transported to the interior of the printer device without fail.

[0034] Next, the internal configuration of the printer device will be described with reference to FIG. 2.

[0035]FIG. 2 is an exploded perspective view for explaining the internal configuration of the printer device shown in FIG. 1.

[0036] As shown in FIG. 2, the housing of the printer device 1 in accordance with the present invention determining the appearance of the printer device 1 is structured with the aforesaid combination of the body cover 2 and body bottom 3. The main frame 12 and a printed-circuit board 22 are stowed in the housing. The main frame 12 is a major component of the printer device and has various mechanisms mounted thereon. The printed-circuit board 22 is placed on the bottom of the main frame 12 and has a shape that is a constituent feature of the present embodiment.

[0037] The main frame 12 consists mainly of a pair of side panels 12 a and 12 b, auxiliary panels 12 c and 12 d, guide panels 13 a and 13 b, and a metallic panel 12 e. The side panels 12 a and 12 b are realized with lightweight metallic plates. The auxiliary panels 12 c and 12 d are attached to the rear edges of the side panels 12 a and 12 b, and realized with lightweight metallic plates. The guide panels 13 a and 13 b has the lower parts of the side edges thereof attached to the lower rear parts of the side panels 12 a and 12 b, realized with lightweight metallic plates, and shaped like letter U. The guide panels 13 a and 13 b block the back of the main frame 12. The recording paper 6 to be transported for printing is brought into contact with the guide panels 13 a and 13 b to be thus guided therewith. The metallic panel 12 e is realized with a lightweight metallic plate. The metallic panel 12 e is located with the side edges thereof fixed to the auxiliary panels 12 c and 12 d, and placed in a space defined with the U-shaped guide panels 13 a and 13 b (inside the printer device). A thermal head driving mechanism 21 for driving the thermal head 20 is mounted on the metallic panel 12 e.

[0038] One of the side panels, that is, the side panel 12 b shown on the right-hand part of the drawing has, as mentioned above, the ink cassette insertion port 2 b through which the ink cassette 7 is inserted. A platen roller 14 is located with the ends thereof fixed to the side panel 12 b and the other side panel 12 a in the internal front space of the main frame 12. The platen roller 14 rotates while clamping the recording paper 6 in cooperation with the thermal head 20 so as to apply pressure required for printing to the recording paper 6, and thus transports the recording paper 6. A pinch roller 15 and a grip roller 40 (see FIG. 6) that are a pair of upper and lower rotary rollers for transporting the recording paper 6 needed for printing are located in front of the platen roller 14. A paper feed roller (or a rubber roller) 18 is located along the edge of the internal front space of the main frame 12 beyond the pair of rotary rollers 15 and 40. The pair of rotary rollers 15 and 40 and the paper feed roller 18 are located with the ends thereof fixed to the front parts of the side panels 12 a and 12 b.

[0039] A recording paper/ribbon feeding mechanism 17 is mounted on the side panel 12 a shown on the left-hand part of the drawing. The recording paper/ribbon feeding mechanism 17 drives the platen roller 14, pinch roller 15, grip roller 40, paper feed roller 18, ink ribbon feed reel 7 b, and ink ribbon take-up reel 7 c so as to rotate them.

[0040] Two motors 16 and 19 are used as a driving source for the recording paper/ribbon feeding mechanism 17. One of the motors, that is, the motor 16 is a stepper motor responsible for all movements to be performed for feeding recording paper in the printer device, and capable of conveying torque to the grip roller 40. The magnitude of an angular motion to be made by the motor 16 can be controlled in order to adjust a magnitude of paper feed by means of a drive control means that is not shown. The other motor 19 is a DC motor that supplies torque to enable the ink cassette 7 to wind up an ink ribbon or enable the paper feed roller 18 to feed paper.

[0041] The stepper motor 16 is mounted on the inner surface of the auxiliary panel 12 attached to the rear edge of the side panel 12 a. The stepper motor 16 is borne by a shaft of a gear 17 a. The stepper motor 16 conveys torque to a rotation shaft of a gear 17 f via a mechanism composed of another gear 17 b meshed with the gear 17 a, a timing belt 17 c, a gear 17 d, a timing belt 17 e, and the gear 17 f. Consequently, torque required for printing is conveyed to the grip roller 40 borne by the rotation shaft of the gear 17 f.

[0042] On the other hand, the DC motor 19 is placed outside the side panel 12 a, and supplies torque to the ink ribbon take-up reel 7 c and paper feed roller 18 so as to enable the ink ribbon take-up reel 7 c to wind up the ink ribbon and to enable the paper feed roller 18 to feed paper. The DC motor 19 conveys torque to the paper feed roller 18, which lies between the side panels 12 a and 12 b, via a gear mechanism 19 a meshed with the rotation shaft of the motor 19. Thus, one sheet of recording paper 6 is fed from the paper feed cassette 5. Moreover, the motor 19 conveys torque to a rotational member 19 b interlocked with the gear mechanism 19 a. This causes the rotational member 19 b to rotate the ink ribbon take-up reel 7 c with which the rotational member 19 b is engaged. Thus, the ink ribbon 7 a is taken up for printing.

[0043] The thermal head 20 and thermal head driving mechanism 21 are located in the space defined with the U-shaped guide panels 13 a and 13 b lying between the auxiliary panels 12 c and 12 d. The thermal head 20 has an exothermic body formed on the front surface thereof opposed to the platen roller 14. The exothermic body sublimates the dyes on the ink ribbon 7 a in the ink cassette 7 so that one screen image can be printed in colors on the recording paper 6 (thermal transfer recording paper). The thermal head 20 is attached to a support member 20 a integrated with a rotation shaft 20 b. With the rotation of the rotation shaft 20 b, the thermal head 20 moves vertically. One side surface of the support member 20 a is always constrained to move towards the thermal head driving mechanism 21 by means of a spring 20 d. When the printer device stands by for printing or has completed printing, the rotation shaft 20 b rotates to cause the thermal head 20 to move upwards due to the constraint given by the spring 20 d. The rotation shaft 20 b is borne by the auxiliary panels 12 c and 12 d that serve as the rear parts of both side surfaces of the main frame 12.

[0044] The thermal head driving mechanism 21 includes a motor 21 a that serves as a driving source for vertically moving the thermal head 20. The motor 21 a is a DC motor and is located in the upper part of the space defined with the U-shaped guide panels 13 a and 13 b in the internal rear part of the main frame 12. The motor 21 a is attached to the metallic panel 12 e, which serves as the back panel of the main frame 12 and is fixed to the side panels 12 a and 12 b, with a support member 21 b between them. The motor 21 a conveys torque via a gear 21 c engaged with the rotation shaft of the motor 21 a. This causes a first cam 21 d that is attached to the rotation shaft of the motor 21 a to rotate. The first cam 21 d is engaged with a second cam 20 c that is located at a right position on the support member 20 a coincident with the position of the first cam 21 d. The support member 20 a supports the thermal head 20. When the support member 20 a pivots with the rotation shaft 20 b as a center, the thermal head 20 makes vertical movements needed for printing.

[0045] Moreover, a rotation shaft 21 g rotates responsively to the movement of a member 21 f engaged with a third cam 21 e. The rotation of the rotation shaft 21 g causes a slider 24 to move straight. The other end of the slider 24 is located inside the side panel 12 b and engaged with a rotational member 15 a that bears the shaft of the pinch roller 15 to cause the pinch roller 15 to move in a predetermined direction. Owing to this structure, when the printer device operates for printing, the pinch roller 15 is moved in the predetermined direction responsively to the vertical movement of the thermal head 20. Moreover, the recording paper 6 clamped by the pinch roller 15 and grip roller 40 is brought into contact with or separated from the thermal head 20 responsively to the movement to be performed for feeding recording paper.

[0046] For accomplishing the aforesaid object of the present invention, the printer device 1 in accordance with the present embodiment has, as shown in FIG. 2, the printed-circuit board 22 interposed between the main frame 12 and body bottom 3. The printed-circuit board 22 has a shape optimal for realizing the compact and lightweight device of the printer device.

[0047] The structure and placement of the printed-circuit board, which are the constituent features of the present invention, and the layout of circuit elements mounted on the printed-circuit board will be described with reference to FIG. 3 to FIG. 5.

[0048]FIG. 3 is a side view for explaining the concept of the printer device, showing the state of the printed-circuit board 22 placed in the printer device shown in FIG. 1. FIG. 4 and FIG. 5 are explanatory diagram concerning the structure of the printed-circuit board. FIG. 4 is a perspective view showing the structure of the printed-circuit board while viewing the printed-circuit board from the front side of the printer device. FIG. 5 is a perspective view showing the structure of the printed-circuit board while viewing the printed-circuit board from the rear side of the printer device.

[0049] The printed-circuit board 22 is, as shown in FIG. 3, placed on the bottom of the printer device 1. The printed-circuit board 22 consists of a control printed-circuit board 22 a and a power printed-circuit board. A group of circuits required for printing, for example, at least one of an IC 31 a (see FIG. 4) for controlling paper feed and an IC 31 b (see FIG. 4) for controlling ink ribbon feed is mounted on the control printed-circuit board 22 a. The power printed-circuit board 22 b is attached to the control printed-circuit board 22 a so that the power printed-circuit board 22 b will be placed along one side surface of the printer device 1. The power printed-circuit board 22 b has battery contacts 34 a (see FIG. 5) that are electrically joined with battery contacts 8 b of the battery 8. The power printed-circuit board 22 b includes a charge circuit element 37 capable of charging the battery 8 brought into contact with the battery contacts 34 a. Thus, the battery that is essential to a portable device can be attached to the printer device, and the charge circuit for charging the battery is incorporated in the printer device. The printer device is therefore realized to be optimally portable.

[0050] The control circuit printed-circuit board 22 a and power printed-circuit board 22 b are coupled to each other with one edge of the power printed-circuit board 22 b attached to one edge of the control circuit printed-circuit board 22 a with a connector 23 between them. The connector 23 serves as a coupling means and is mounted on a lower marginal part of the control circuit printed-circuit board 22 a. The coupled printed-circuit boards are shaped substantially like letter L. When the connector 23 is used to couple the power printed-circuit board 22 b to the control printed-circuit board 22 a, a lower marginal part of the power printed-circuit board 22 b may be directly inserted into the connector 23 in order to retain the L shape of the assembled printed-circuit boards. Alternatively, as shown in FIG. 3, both the printed-circuit boards 22 a and 22 b may have connectors. In this case, when the connectors are joined, the L shape of the assembled printed-circuit boards is retained.

[0051] The thus-structured printed-circuit board 22 is placed in the housing composed of the body cover 2 and body bottom 3 along the inner wall of the housing.

[0052] Moreover, a group of circuits required for printing, for example, the IC 31 a for controlling paper feed, the IC 31 b for controlling ink ribbon feed, and a video signal processing circuit that is not shown are, as shown in FIG. 4, mounted on the control printed-circuit board 22 a included in the printed-circuit board 22 employed in the present embodiment. Moreover, a memory card connector 9 a and a PC connector 11 a are mounted along one side edge of the control printed-circuit board 22 a. The memory card 9 is loaded in the memory card connector 9 a so that it can be unloaded freely. The PC connector 11 is joined with the PC connector 11 a so that it can be disjoined freely. Furthermore, a plurality of connectors 30 a, 30 b, 30 c, 30 d, 30 d, 30 e, 30 f, and 30 g through which various electronic components (not shown) incorporated in the printer device are connected to circuits is arranged along the front edge of the control printed-circuit board 22 a.

[0053] The circuits and connectors are electrically connected to one another over a printed pattern 31 c that is a pattern printed on the control printed-circuit board according to required routings of signals.

[0054] By the way, the power printed-circuit board 22 b and the control printed-circuit board 22 a are assembled in the shape of letter L using the connector 23. The circuit elements mounted on the power printed-circuit board 22 b are electrically connected to various electronic parts mounted on the control printed-circuit board through the connector 23. The power printed-circuit board 22 b has a notch 33 formed in the lower center thereof that borders the control printed-circuit board 22 a. A joint member 34 including the battery contacts 34 a that are electrically joined with the battery contacts 8 b of the battery 8 is locked in the notch 33.

[0055] The charge circuit element 37 for charging the battery 8, the control IC 38 for controlling the thermal head 20 and thermal head driving mechanism 21, and others are mounted on the inner surface of the power printed-circuit board 22 b. Furthermore, connectors 32 a and 32 b through which the circuit elements on the power printed-circuit board 22 b are connected to the thermal head driving mechanism 21 and a large-scale capacitor (not shown) are mounted along one side edge of the power printed-circuit board 22 b.

[0056] The joint member 34, charge circuit element 37, and control IC 38 are, as shown in FIG. 5, electrically interconnected over a printed pattern 37 a that is a pattern printed on the power printed-circuit board according to required routings of signals.

[0057] At least three battery contacts 34 a are, as shown in FIG. 5, projected from the outer surface of the joint member 34 locked in the lower center of the power printed-circuit board 22 b. When the battery 8 is fitted in the battery attachment groove 2 c in the body cover 2, the battery contacts 34 a of the joint member 34 come into contact with the battery contacts 8 b of the battery 8 so as to conduct. Consequently, power stored in the battery 8 is supplied to the body of the printer device 1.

[0058] As mentioned above, the printed-circuit board 22 incorporated in the printer device 1 in accordance with the present embodiment consists of the control printed-circuit board 22 a and power printed-circuit board 22 b that are assembled substantially in the shape of letter L. Furthermore, the control circuits including the circuits for controlling recording paper feed and controlling ink ribbon feed are mounted on the control printed-circuit board 22 a placed on the bottom of the printer device. On the other hand, the circuit for driving the thermal head and the charge circuit that handle relatively high power are mounted on the power printed-circuit board 22 b placed along the back surface of the printer device.

[0059] In other words, the power printed-circuit board 22 b on which relatively large current flows is located near a large current source, that is, a component from which large current flows. Moreover, the charge circuit, the battery contacts 34 a, and the control circuit for applying voltage to the thermal head 20 to heat the thermal head 20 are mounted and concentrated on the sole power printed-circuit board 22 b. On the other hand, the control printed-circuit board 22 a responsible for control of recording paper feed and control of ink ribbon feed that require only small current is located near a small current source, that is, an actuator (including the recording paper/ribbon feeding mechanism 17) needed for feeding the recording paper and ink ribbon. Moreover, the circuits for controlling recording paper feed and controlling ink ribbon feed are mounted and concentrated on the sole control printed-circuit board 22 a. In the printer device 1, only the printed-circuit board 22 composed of the power printed-circuit board and control printed-circuit board and shaped like letter L is incorporated in order to realize the abilities of the printer device. The printed-circuit board 22 is a motherboard. This leads to the reduced lengths of routings of signals, and results in the compact and lightweight printer device. Thus, the printer device is optimally portable.

[0060] Since the printed-circuit board 22 is composed of the two printed-circuit boards 22 a and 22 b, the printed-circuit boards are manufactured mutually independently. This is advantageous in terms of a manufacturing process. Specifically, the printed-circuit boards can be assembled with the right part of the other substrate inserted directly into the connector. Before the assembling, the jobs of mounting electronic parts on the printed-circuit boards can be carried out separately. The assembling job is therefore simple. This greatly contributes to simplification of the manufacturing process and reduction in the cost of manufacturing.

[0061]FIG. 6 is a sectional view of a major portion of the printer device having the aforesaid printed-circuit board 22 actually incorporated therein. Movements to be made in the printer device in accordance with the present embodiment will be described in conjunction with FIG. 6.

[0062] To begin with, the topmost sheet of recording paper 6 stowed in the paper feed cassette 5 is fed to the interior of the printer device 1 by the paper feed roller 18. At this time, the recording paper 6 is smoothly fed with the rotation of the paper feed roller 18 because of the presence of a member having a curved surface at the proximal end of the paper feed cassette 5 inserted deeply in the printer device.

[0063] Guide plates 41 a, 41 b, and 41 c that are attached to the main frame 12 in order to define recording paper transportation paths 43 a and 43 b are arranged in a stage preceding the stage in which the pinch roller 15 and grip roller 40 are located in the inner front space of the printer device. The recording paper 6 fed by the paper feed roller 18 passes through the transportation path 43 a defined with the guide plate 41 b while thrusting up a tape member 42 attached to the guide plate 41 c. The recording paper 6 is thus transported towards the pinch roller 15 and grip roller 40. At this time, a sensor located near the recording paper transportation path defined with the guide plate 41 b detects whether the recording paper 6 is normally transported, though the sensor is not shown. Depending on the result of detection, a major control unit mounted on the control printed-circuit board 22 a determines whether printing should be started. If the recording paper is not transported normally, the control unit instructs display of an error indication or the like on a display unit 2 e formed on the top of the body cover 2. Otherwise, control is given to drive components required for starting printing.

[0064] When printing is started, the recording paper 6 is clamped by the pinch roller 15 and grip roller 40. The IC 31 a for controlling recording paper feed mounted on the control printed-circuit board 22 a controls driving of the recording paper/ribbon feeding mechanism 17. Moreover, the grip roller 40 having an anti-slipping means applied to the surface thereof is driven to rotate. Consequently, transportation of the recording paper 6 for printing is controlled. In other words, transportation of the recording paper 6 is controlled so that the distal part of the recording paper 6 will be transported through the recording paper transportation path 44 defined with the guide panels 13 a and 13 b. At this time, the rear part of the recording paper 6 reaches a printing start point between the thermal head 20 and platen roller 14.

[0065] During printing, since the grid roller 40 and pinch roller 15 rotate, the recording paper 6 and ink ribbon 7 a are fed while being pressed by the thermal head 20 and platen roller 14. While the recording paper is being fed, the control circuit mounted on the power printed-circuit board 22 b causes current to flow into the exothermic body of the thermal head 20. Consequently, the thermal transfer inks on the ink ribbon 7 a are dissolved or sublimated and transferred onto the recording paper 6. Printing is thus achieved. Moreover, during the printing, the circuit for controlling ink ribbon feed controls feed of the ink ribbon 7 a required for printing.

[0066] In this case, for transferring the first ink of yellow (Y) on the ink ribbon 7 a onto the recording paper 6, the pinch roller 15 and grip roller 40 feed the recording paper 6 to the left-hand part of the drawing. The recording paper 6 and ink ribbon 7 a are fed while being pressed by the thermal head 20 and platen roller 14. An image information signal representing yellow (Y) is applied to the exothermic body (not shown) of the thermal head 20.

[0067] At this time, the distal part of the recording paper 6 runs through the recording paper transportation path 44 defined with the U-shaped guide panel 13 a and the U-shaped guide panel 13 b placed inside the guide panel 13 a. On the other hand, the rear part of the recording paper 6 passes through the transportation path 43 a, thrusts down the tape member 42 attached to the guide plate 41 c, and reaches the recording paper transportation path 43 b. Meanwhile, the first color ink is transferred.

[0068] The position of the thermal head 20 for printing can be selected from among three positions. The three positions, for example, an upper position, a lower position at which the thermal head is located in the drawing, and an intermediate position that is referred to as a partial position and at which the thermal head stands by are switched by the thermal head driving mechanism 21. Depending on a printing mode, the position of the thermal head 20 is controlled by the control IC 38 mounted on the power printed-circuit board 22 b.

[0069] After transferring the first color ink of yellow (Y) onto the recording paper 6 is completed, the control IC 38 gives control to drive the thermal head driving mechanism 21. Consequently, the thermal head 20 is parted from the platen roller 14 and moved to the partial position. Furthermore, the pinch roller 15 and grip roller 40 feed back the recording paper 6 to the rear part of the printer device 1 (to the right-hand part of the drawing). The aforesaid movements are repeated in order to transfer the second color ink of magenta (M), the third color ink of cyan (C), and the transparent overcoat (OP) onto the recording paper 6 in that order. Thus, color printing is achieved.

[0070] The recording paper 6 is kept fed back to the rear part of the printer device 1 (to the right-hand part of the drawing) by the grip roller 40 and pinch roller 15 until transfer of color inks is started. At this time, the distal part of the recording paper 6 is fed while being guided by the recording paper transportation path 44 defined with the U-shaped guide panels 13 a and 13 b. The sensor that is not shown detects the rear part of the recording paper 6. The rotation of the pinch roller 15 and grip roller 40 is controlled based on the result of detection, whereby the rear part of the recording paper 6 is set at the printing start point between the thermal head 20 and platen roller 14.

[0071] When transfer of all color inks is completed, the printed recording paper 6 is ejected to outside the printer device through the recording paper transportation path 43 b by means of a paper feeding mechanism that is not shown and that ejects paper. Printing is thus completed.

[0072] According to the present embodiment, the power printed-circuit board 22 b on which large current flows is located near a large current source. Moreover, the charge circuit, the battery contacts 34 a, and the control circuit for applying voltage to the thermal head 20 so as to heat the head are mounted and concentrated on the sole power printed-circuit board 22. The control printed-circuit board 22 a responsible for control of recording paper feed and control of ink ribbon feed, which require only small current, is located near a small current source, that is, an actuator needed for feeding the recording paper and ink ribbon (including the recording paper/ribbon feeding mechanism 17). The circuits for controlling recording paper feed and controlling ink ribbon feed are mounted and concentrated on the sole control printed-circuit board 22 a. In the printer device 1, only the printed-circuit board 22 composed of the two printed-circuit boards and shaped like letter L need be incorporated in order to realize the abilities of the printer device. The printed-circuit board 22 is a motherboard. This results in a compact and lightweight printer device, and enables provision of a printer device that is optimally portable.

[0073] Since the printed-circuit board 22 is composed of the two printed-circuit boards 22 a and 22 b, the printed-circuit boards 22 a and 22 b can be manufactured mutually independently and assembled easily. This is advantageous in terms of a manufacturing process for the printed-circuit board. Besides, the manufacturing process can be simplified. This greatly contributes to reduction in cost of manufacturing.

[0074] The present invention is not limited to the aforesaid embodiment. The applications of the embodiment are encompassed by the present invention.

[0075] As described so far, according to the present invention, a printer device can be designed to be compact and lightweight, and thus realized to be optimally portable. Moreover, since the printed-circuit board 22 employed in the printer device 1 has an easy-to-manufacture structure, the manufacturing process can be simplified. This greatly contributes to reduction in the cost of manufacturing. 

What is claimed is:
 1. A printer device comprising: a control printed-circuit board placed on the bottom of said printer device, and including a control circuit for controlling at least one of paper feed and ink ribbon feed; a power printed-circuit board placed along one side surface of said printer device, and including a charge circuit for charging a rechargeable battery brought into contact with battery contacts connected to the charge circuit; and a coupling means for electrically coupling said control printed-circuit board to said power printed-circuit board.
 2. A printer device according to claim 1, wherein: said control printed-circuit board and said power printed-circuit board are coupled to each other with one edge of said control printed-circuit board joined with one edge of said power printed-circuit board; and the coupled printed-circuit boards are shaped substantially like letter L and placed along the inner wall of the housing.
 3. A printer device according to claim 1, wherein said control printed-circuit board and said power printed-circuit board are coupled to each other using a connector which is mounted on one printed-circuit board and into which a right part of the surface of the other printed-circuit board is directly inserted.
 4. A printer device according to claim 1, wherein said control printed-circuit board and said power printed-circuit board are coupled to each other by joining connectors that are mounted on said printed-circuit boards.
 5. A printer device according to claim 1, wherein said power printed-circuit board is located along the back surface of said printer device.
 6. A printer device according to claim 1, wherein said power printed-circuit board includes a control circuit that controls a thermal head.
 7. A printer device according to claim 6, wherein said thermal head is located near the top of said printer device, and an actuator means needed for feeding paper or an ink ribbon is locate d near the bottom of said printer device. 